There have been conventionally known respiratory protection devices in which a filter unit inclusive of a filter for removing dust and the component of poisonous gases is mounted on a facepiece. Also, there have been conventionally known respiratory protection devices in which a plurality of filter units are mounted on the facepiece.
For example, a protection mask disclosed by Japanese Unexamined Patent Application Publication No. 2007-181570 (P2007-181570A, Patent Literature 1) includes filter units respectively mounted on the bilateral sides of a center line that bisects the width of a facepiece. Respective filter units are linked to the inner side of the facepiece through separate inhalation ports formed in the facepiece. In the facepiece, a check valve for inhalation is mounted to each of the inhalation ports. A filter incorporated in the filter unit can be detachably provided to a cup in the filter unit.